Introductory Chapter: Open Problems and Enabling Methodologies for Smart Grids DOI: http://dx.doi.org/10.5772/intechopen.86496

It distinguishes seven different functional areas in smart grids, called domains. Each domain is characterized by a set of actors and applications that perform actions on energy and data inside the domain and allow the exchange of power and information between domains, by means of different interfaces, also called domain gateways.

The next sections describe the main features of each domain and the related key technologies.

### 2.1 Bulk generation

This domain collects all the actors and the applications related to the centralized generation of large amounts of power, optimally dispatched in order to satisfy the predicted demand. In traditional power systems, characterized by one-way power flows, this was the only domain in which power was produced.

The importance of this domain is not only due to the production of a high percentage of the total required power but also due to the ancillary services it offers in order to maintain stability and security of the whole power system.

This domain has communication interfaces to market, operation, and transmission domains, although it is electrically coupled only to transmission network.

#### 2.2 Transmission domain

Transmission infrastructures allow the efficient transfer of electrical power from generators to distribution systems. Their main components are high-voltage power lines, substations, sensors, and protection systems. Their correct operation and maintenance is entrusted to transmission system operators (TSOs). The evolution of power systems toward smart grids is leading to the development of several innovative technologies to improve power transmission's reliability and efficiency [5]. The most impactful ones are advanced power electronic-based systems, such as flexible AC transmission systems (FACTS), that enhance controllability and increase power transfer capability of transmission systems.

### 2.3 Market domain

Market domain is where prices for power exchanges are established. Currently, electricity markets are changing in order to fully exploit the possibilities introduced by future smart grids.

Market domain is connected by communication paths to every other domain. It receives information regarding system's state and constraints by the operators and service providers and proceeds to dispatch generated power in order to satisfy the demand.

Communications between market domain and the other ones must be secure, reliable, and transparent and with low latency in order to correctly operate the system.

Future power systems include a more active participation from the customer's side, thanks to the integration of demand-side management paradigms or the aggregation of various distributed generation and loads in the so-called virtual power plants.

#### 2.3.1 Virtual power plants

Virtual power plants (VPPs) are a smart management paradigm consisting in coordinating generating units with different characteristics, stochastic or dispatchable ones, flexible profitable loads, and storage units in order to maximize

addressing some challenging open problems, which could hinder their deployment

The most widely accepted smart grid's conceptual model has been developed by the National Institute of Standards and Technology (NIST) (Figure 2) [4].

in existing power grids, will be outlined (Figure 2).

Comparison between traditional grid and smart grid [1].

Research Trends and Challenges in Smart Grids

2. Conceptual model

NIST conceptual model [4].

Figure 2.

2

Figure 1.

the total profit [6]. Generation and consumption are managed in such a way that the market sees VPPs as a single flexible power output toward the grid.

however, all other customers benefit from the lower prices due to diminished demand peaks. Market performance is improved due to the lower market power of the producers, and operators have another flexible tool to address power systems'

Introductory Chapter: Open Problems and Enabling Methodologies for Smart Grids

Operation domain is the set of actor and applications required for the reliable, safe, and efficient operation of power systems. The main duties are related to planning, monitoring, protection, maintenance, and control of power systems. The increasing diffusion of distributed renewable energy sources is posing a series of challenges to operators. Traditional power systems were designed for one-way power flows, while in modern grids, backward flows are frequent. Furthermore, the intermittent nature of solar and wind energy requires special attention to avoid

Smart grids are improving operators' capabilities with advanced technologies.

Wide area monitoring systems (WAMS) are an emerging paradigm, involving the utilization of system-wide information to prevent the propagation of large disturbances, increasing the efficiency of the transmission system, and providing better protection and control [8]. Their development was possible thanks to the diffusion of advanced measurement systems: the phasor measurement units (PMU)

The main difference between these sensors and the supervisory control and data acquisition (SCADA) systems is that they are all synchronized to a common reference time, and thus they can measure and compare the phase angles from voltage phasors of busses contained in a wide area control region. They allow a series of useful applications: state estimation, voltage stability control, dynamic thermal

The path toward a smarter grid implies the deployment of WAMS in power

Smart meters are advanced energy meters that offer a wide range of functions, such as storage of detailed consumption data, two-way communication with utilities, and support for dynamic pricing, enabling demand response and monitoring of power quality and disturbance events. A proper deployment of such systems requires an automated metering infrastructure (AMI) that is a two-way communi-

Through AMIs, utilities can improve their analytic capabilities and operate systems in a more efficient, economic, and reliable way. Despite the benefits, AMIs could expose the system to a series of cyber security and customer's privacy threats; thus, they must be carefully designed in order to ensure the protection against

Distribution domain is electrically connected to the transmission domain and to

the customer's domain. It is at lower voltage levels, and it is where most of the

distributed generation has been installed during the last years.

technical problems.

2.4 Operation domain

system's imbalances and stability problems.

DOI: http://dx.doi.org/10.5772/intechopen.86496

2.4.1 Wide area monitoring systems

that are the basic elements of WAMS.

systems worldwide.

2.4.2 Smart meters

cyberattacks.

5

2.5 Distribution domain

rating, congestion management, and fault localization.

cation network linking a huge number of smart meters.

The need for this new energy management paradigm is a consequence of the uncertainty and unreliability introduced by the diffusion renewable energy sources, in particular wind and solar power.

Introduction of a VPP leads to less risky and more efficient bidding in electricity markets, since bad predictions of renewable production can be adjusted by dispatchable generators, flexible loads, and energy storage. Furthermore, this paradigm allows the indirect access of renewable energy sources to the ancillary service markets, increasing their potential integration in power systems.

From the point of view of network operators, VPP simplifies system's management, since uncertainties and imbalances are locally addressed by the aggregator, which can assure a secure or at least less uncertain power production.

### 2.3.2 Demand response

Demand response refers to the active participation of customers to power system's balancing, requested by grid operators. Customers are encouraged to modify their load pattern by changes in price of electricity or incentive payments [7].

The transition toward smart grids is an essential element for the development of the demand response paradigm, since it requires advanced monitoring, communication, and control systems, in order to be correctly implemented in future power systems.

From the customer's point of view, the participation in a demand response program requires one of the following actions:


Market operators can act on the demand response using different strategies that can be classified in three main branches:


Demand response has several benefits related to different domains. Customers participating in demand response programs have direct economical rewards;

however, all other customers benefit from the lower prices due to diminished demand peaks. Market performance is improved due to the lower market power of the producers, and operators have another flexible tool to address power systems' technical problems.
